Everolimus in ER + /HER-2 negative metastatic breast cancer (MBC): what we have learned from two years of clinical practice. A single Institution experience

Abstract

Background: The everolimus-exemestane pair was approved by the US Food and Drug Administration (FDA) in 2012 to treat women with hormone receptor-positive (ER+), HER2-negative metastatic breast cancer (MBC) that got worse after treatment with aromatase inhibitor alone. The main benefit of this regimen is that it is less toxic than chemotherapy and offers patients a better quality of life. Patients and method: We have evaluated the efficacy and safety of exemestane and everolimus in post-menopausal patients with ER + /HER-2 negative MBC after progression with aromatase inhibitors. Patients were evaluated for adverse events (AEs) and serious adverse events (SAEs) graded according to NCI-CTC for AEs (version 3). Results: Between September 2012 and April 2015, in our Institution, 30 consecutive patients with MBC were treated with the daily combination of everolimus and exemestane. 63.4% of patients received everolimus and exemestane within the first three lines of treatment. The median age was 66 years (51-82). 43.3% of patients had asymptomatic visceral metastases. Of all patients, 3.3% had a complete response (CR) and 13.3% a partial response (PR); 30% had a stable disease (SD) while 36.7% had a progressive disease (PD). 5 patients were not evaluable because it is too early. Median PFS was 7.1 months (1.57-26.8). 4 patients have continued the treatment for more than 20 months. The most common toxicities were stomatitis (56.6%), asthenia (23.3%), neutropenia (20%) and rash (16.6%). However only 4 cases of G3 adverse events require a reduction of everolimus administration to 5 mg every day. Conclusions: Our experience, although with a small number of patients, demonstrates that oral mTOR inhibitor everolimus in ER + /HER2-negative post-menopausal MBC has a similar efficacy and safety profile compared to the BOLERO-2 trial. In this patient population, everolimus is generally well tolerated and the appropriate management of treatment-related AEs is fundamental to improving patient quality of life and treatment outcomes.